Dry marks (?) that are not going away w/ PEC-12

[kiss-o-matic]

Hi
I've recently developed a bunch of rolls of Rollei Retro 80s in Rodinal. A roll or two seem to have some dry marks. I did use Photo Flo 200 for all the rolls, so I'm scratching my head a bit at these two. A good candidate to show is a pic taken vertically w/ my Fujifilm TX-1. The kicker is, I've wiped both sides w/ PEC PADS + PEC12 which is apparently safe to do, but I've seen no change. (Applied PEC12 to PEC PAD, swiped 2-3 times in one direction without applying too much form, but what I'd assume is enough for a water mark).

For the record, I did 1+100 stand for 60 minutes. 3 agitations to start, 1 at 30 minutes. 1 minute bath in water w/ Photo Flo at the suggested dilution. Vigorously shook out the water, no squeegee (even fingers) and then let hang dry. I've not developed in a few years due to the pandemic but I think maybe I did squeegee w/ my hands prior. Worth noting is I did not use Distilled Water. I can't for the life of me find any near me (supply chain issue?) and got impatient.

 

[koraks]

Are these drying marks or uneven development marks? Can you photograph the shiny side of an affected area of the film at an oblique angle so as to clearly show any reflectance differences? Does visual inspection of the film show any density differences in the silver image?

 

[kiss-o-matic]

The shiny party looks normal -- eg, I see no reflective difference when I shine light on it. So, I guess maybe that's uneven development marks? What generates that though? Not enough agitation? The tank was definitely full to to the top.

 

[koraks]

So, I guess maybe that's uneven development marks?

That's what it would seem like, yes.

What generates that though? Not enough agitation?

Likely. To be fair, you are flirting with this kind of problem by doing stand development.

 

[AgX]

Anyway, the PEC-12 is an organic solvent. It only may take off anything that it can dissolve or any particles that sit loose on a surface that can withstand such solvent.
Any salts (thus salts coming with or created within an aquous solution) will likely be stuck to or within the gelatin surface. In such cases you rather need an chemically active potion as an acid.

 

[koraks]

Any salts (thus salts coming with or created within an aquous solution) will likely be stuck to or within the gelatin surface.

In my experience actual drying marks are usually present on the non-emulsion (shiny) side of 35mm film. At least the marks that are visible and problematic; there may be invisible ones within the gelatin emulsion as well, but I never noticed them. Taking the marks off the shiny side usually succeeds by mechanical means only; for instance using a non-pilling, soft fiber cloth. However, this can still bring the risk of scratching; it only takes a single grain of sand....
What I generally do in cases of drying marks or debris, is soak the film in water, then use a very soft hair brush to gently wipe the affected surface(s) of the film, soak in distilled water and dry. This is generally effective and does no damage - provided a suitable brush is used and no force is applied.

I quite like your idea of an acid treatment for classic drying marks (lime scale); dilute acetic acid would do the trick just nicely and won't damage the film in any way. It may not be very effective for larger deposits, such as chunks of scale that dislodged from unclean equipment.

 

[AgX]

Taking the marks off the shiny side usually succeeds by mechanical means only; for instance using a non-pilling, soft fiber cloth. However, this can still bring the risk of scratching; it only takes a single grain of sand....

As long as the back of the film-strip is not coated too, a apt aqueous compound can be used too in assisting wiping off there.

 

[koraks]

True, and in my experience, the films that also have a backside coating aren't prone to drying marks, so the issue generally doesn't pop up there. As they sometimes say in statistics, "on average, everything stays the same". Sometimes things tend to sort of even out in practice.

 

[kiss-o-matic]

Thanks for the tips guys. I think the stand development maybe what got me here. Lesson learned.